The past decade has witnessed a notable increase in research pertaining to microbicides and their associated use in pharmacological applications. One particular area of increased research is HIV/AIDS research.
A substantial amount of research into microbicidal chemical agents that are applied intravaginally to prevent transmission of sexually transmitted diseases, including HIV-1, has been conducted in the recent past. One of the major motives for conducting this research is that these agents can shift the sexually transmitted infection (STI) prevention dominion from male to female.
Many such microbicidal chemical agents have proven to be effective in vitro but this has not been the case in vivo and, in consequence, no anti-HIV-1 microbicide is available on the market. The translational failures of microbicides have been attributed to various factors, among them the fact that some microbicidal agents, though effective in deterring the HIV-1 virus, also diminishes the host's defence mechanisms as exemplified by the nonoxynol-9 gel which disrupts the barrier properties of the vaginal mucosa (Van damme et al., 2002). Other challenges faced in this area of research include the ability to deliver these potent anti-HIV-1 microbicidal agents in a manner in which they retain their potency, tailoring said agents to be successfully distributed in a site specific manner (particularly intravaginally), and controlling their residence time at the specific site such that they are quantitatively sufficient to effectively prevent HIV-1 transmission.
Various pharmaceutical anti-HIV-1 microbicidal formulations have been invented including vaginal tablets, rings, films and gel formulations, most of which are fast, yet short acting delivery systems applied prior to and after coitus. There is a need to develop pharmaceutical dosage forms having an increased residence time at their target sites. There is further a need for a more ergonomic pharmaceutical dosage form to be developed relative to the existing intravaginal pharmaceutical dosage forms on the market, which include gels which have been reported to be messy and sticky. It remains important that the pharmaceutical dosage forms deliver at least one pharmaceutical compound, extensively and exclusively, at a specific target site.